Both, Mob1s1a1 (SIM1) and Mob1s2a1 (SIM2) interfaces are logical interfaces for the wwan0 interface. In the WebUI, there should be no wwan0 and you should only see the logical mob1s1a1 and mob1s2a1 interfaces. Could you please clarify why the wwan0 interface is in the failover menu?
I would suggest updating the device to the latest firmare version which can be downloaded from here. Please, update with ‘keep settings’ option disabled to ensure that there are no issues after the update. However, keep in mind that this will erase your current configurations and you will need to reconfigure the device. So if the device is in a remote location and you do not have access to it, please avoid updating the device as you may lose remote access.